Study of changes in unripened soft rennet-curd cheeses caused by the addition of dried nettle leaves: Physicochemical properties, microbial quality, polyphenol content, and sensory characteristics

Abstract

The objectives of the study were to investigate changes in the number of selected groups of microorganisms and the level of antioxidant activity during storage of model unripened cheeses with the addition of dried nettle leaves, to compare their sensory characteristics, as well as to determine the antioxidant properties of the obtained whey. Three groups of model unripened rennet-curd cheeses were produced: I—a control sample without a plant additive, II and III—samples with the addition of dried nettle leaves in the amount of 0.165% and 0.330% (g/100 g of milk), respectively. Advantageously, no effects of nettle addition on total microbial and Lactococcus counts were determined. Moreover, the application of this herb slowed down the yeast and mold growth in cheese, increased the antioxidant activity, and elevated the contents of total polyphenols, caffeic acid, p-coumaric acid, rutin, and ferulic acid. Additionally, the antioxidant properties of the obtained whey were also higher in comparison to control. Sensory analysis revealed that the addition of a lower amount (0.165%) of dried nettle leaves appeared to be the most favorable option, balancing improved nutritional and antioxidant value with acceptable sensory characteristics and acceptability. The study demonstrated that the application of dried nettle leaves as an addition to cheese offers many benefits.